Abstract:Adsorptive fractionation of macrophyte- and algae-derived dissolved organic matter (MDOM and ADOM) on goethite was investigated to demonstrate the transfer of autochthonous DOM at the water-sediment interface in eutrophic lakes. Excitation emission matrix spectra with parallel factor analysis showed that protein-like substances, including tyrosine- and tryptophan-like component (C2 and C3), accounted for 70% and 93% of total fluorescent components in MDOM and ADOM, respectively. While, contents of humic acid- and fulvic acid-like components (C4 and C1) were limited in both DOMs. The two DOMs were effectively adsorbed on goethite and this adsorption process can be well simulated by pseudo-first order kinetic equation. Fitting by adsorption isotherm revealed the stronger, more nonlinear adsorption of ADOM (23.77 mg/g of Qmax) on goethite than MDOM (19.10 mg/g of Qmax). Specifically, a nonlinear adsorption was found between protein-like substances and goethite, whereas the adsorption of humic-like substances was almost linear. The adsorption capacity of DOM components to goethite followed the order of: C3 > C2 > C4 > C1, which was dependent on their initial content, molecular weights, aromaticity, and binding sites. Infrared spectroscopy further indicated that amino, carboxyl, and hydroxyl were responsible functional groups for the heterogeneous adsorption. Overall, the production of ADOM and MDOM significantly changes the organic compositions on goethite surface and affects the biogeochemical cycles in lake sediments.